The present invention relates to a cannulated bone fixation screw that can be inserted with the aid of a guide pin. The cannulated screw according to the present invention is useful for the surgical repair of injured bones, tendons, and ligaments.
A relatively common injury involves complete or partial detachment of tendons, ligaments or other soft tissues from their bony attachment points. Partial detachment, commonly known as a sprain, will generally heal given sufficient time. However, if the ligament or tendon is completely detached from the bony attachment points, or is severed by a traumatic injury, partial or permanent disability can result if surgical attention is not given soon after the injury. Detachment of ligaments frequently occurs among certain types of athletes such as football players due to the unusual stresses placed on ligaments during normal play. Fortunately, detachment due to external trauma or mechanical overextension of a ligament or tendon can be surgically corrected in many cases.
A typical surgical correction of a tendon or ligament injury involves the fixed attachment of the tendon or ligament substitute to the area of normal bony attachment so that regrowth and reattachment of the tendon or ligament substitute to the bone is enabled. Attachment of the ligament substitute to the bone is ensured by the use of bone attachment means such as metal staples, sutures over buttons, or cancellous bone screws. The ligament substitute to bone attachment means must be rigidly situated so that regrowth of the ligament substitute in the bony area of the attachment point is uninterrupted by any later disattachment due to stress.
The prior art devices for reattachment are not uniformly successful, especially in those instances when the occupation or lifestyle of the recipient of the reattachment procedure is very active. A common problem with the prior art attachment methods is their failure under the normal tensile loads to which the attachment means is subjected, which can cause further soft tissue damage requiring more corrective surgery. A further problem with conventional cancellous bone screws is the difficulty encountered in the successful insertion of the screw in the correct position and orientation due to inadequate screw size, poor bone quality, or poor surgical technique. Accurate positioning of the screw is necessary to ensure a close interference fit where the screw imparts a significant compressive load against the bone plug so that the bone plug becomes intimate with the bone hole.
It is accordingly the object of the present invention to provide an attachment device for reconnection of detached or severed soft tissues to their bony attachment points that is capable of being accurately positioned.
It is further object of the present invention to provide a self-tapping bone screw using flutes cut into the threads of the bone screw, with the bone screw further having an axial cannula suitable for use in conjunction with a guide pin for proper positioning of the bone screw in a bone bore hole.
Another object of this invention is to provide a fluted, self-tapping bone screw having an axial cannula suitable for use in conjunction with a guide pin for proper positioning of the bone screw in a bone bore hole so that an interference fit between a bone plug with attached ligament substitute, the bore hole walls, and the bone screw is created.
One further object of this invention is to provide a method for the reattachment of soft tissues to bony attachment points by providing a fluted, self-tapping bone screw having an axial cannula suitable for use in conjunction with a guide pin that ensures proper positioning of the bone screw.
According to the present invention, an apparatus and method suitable for providing a secure attachment point in cancellous bone is provided. The apparatus includes a bone screw having an axially centered cannula with a diameter corresponding to the diameter of a guide pin that has been preinserted into a bone bore hole. The bone screw is self-tapping, having flutes cut into the threads that act to cut internal threads into cancellous bone in the bone bore. A common method of employment of the bone screw of the present invention is to provide an interference fit between a bone plug attached to a ligament substitute and inserted into the bone bore hole, and the sides of the bone bore hole. In this situation the bone screw will act to permanently compress the bone plug against the bore hole wall, providing a stable attachment point to permit the bone plug and the bone bore hole to become one to permit for ligament substitute regrowth and revitalization.